An amplifier circuit includes an amplifier circuit that emitter-grounds a first transistor that amplifies an input signal; and an emitter-grounded feedback circuit in which a collector of the first transistor is connected to an output line of the amplifier circuit and a base is wiring-connected only to the output line by using a resistor.
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10. An amplifier circuit, comprising:
an emitter-grounded amplifier circuit that amplifies an input signal as a voltage amplifier, the emitter-grounded amplifier circuit being a common emitter amplifier circuit; and
an emitter-grounded feedback circuit that includes a transistor of which a collector is connected to an output line of the amplifier circuit and a base of a feedback transistor is coupled with the output line via a resistor.
1. An amplifier circuit, comprising:
an input-part amplifier circuit that emitter-grounds a first transistor that amplifies an input signal as a voltage amplifier, the input-part amplifier circuit being a common emitter amplifier circuit; and
an emitter-grounded feedback circuit in which a collector of the first transistor is connected to an output line of the input-part amplifier circuit, and a base of a feedback transistor is wiring-connected only to the output line by using a resistor.
2. The amplifier circuit according to
the input-part amplifier circuit is a differential amplifier circuit that includes a second transistor, the second transistor making a pair with the first transistor, and a pair of output lines of a positive phase and a reversed phase, and
in the feedback circuit, a pair of transistors and a pair of resistors are provided, a base of one transistor is connected to a collector of the one transistor that is connected to the positive phase between the pair of output lines, and a base of the other transistor is connected to a collector of the another transistor that is connected to the reversed phase.
4. The amplifier circuit according to
5. The amplifier circuit according to
6. The amplifier circuit according to
an emitter-follower circuit that is provided on an output stage of the output line; wherein
an input of the emitter-follower circuit is connected to the collectors of the transistors of the input-part amplifier circuit and an output of the emitter-follower circuit is feedback-connected to the bases of the transistors of the feedback circuit.
7. The amplifier circuit according to
a laser element that is connected to an output terminal of the output line; wherein
the laser element is driven to emit light by the amplifier circuit.
8. The amplifier circuit according to
a laser element that is connected to an output terminal of the output line; wherein
the laser element is directly driven to emit light by the emitter-follower circuit.
9. The amplifier circuit according to
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This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2012-250540, filed on Nov. 14, 2012, the entire contents of which are incorporated herein by reference.
The embodiments discussed herein are related to an amplifier circuit which amplifies a signal.
In recent years, speeding up of a data rate has been advanced so as to transmit a large volume of data by one signal, along with increase of a data communication amount in a field of communication. With this speeding up, a circuit which meets a high speed for amplifying, shaping, and driving a high-speed signal is demanded. As an amplifier circuit for amplifying a signal, a grounded-emitter amplifier circuit, a differential grounded-emitter amplifier circuit thereof, and the like are widely used. In these amplifier circuits, parasitic capacitances of collector of a transistor, a wiring, an additional circuit, and the like cause deterioration of a band, an insufficient frequency property (lack of a high frequency range), and insufficient rising/falling in an eye waveform, and jitter increase, bringing difficulty in speeding up.
A feedback type high-speed amplifier circuit (refer to FIG. 2 of Justin Abbott, Calvin Plett, John W. M. Rogers, “A 15 GHz, 1.8V, Variable-Gain, Modified Cherry-Hooper Amplifier”, IEEE 2005 CUSTOM INTEGRATED CIRCUITS CONFERENCE, 22-5-1 to 22-5-4, p.645 to p.648, for example) has been disclosed as a speeding-up measure. This circuit subtracts low-speed components from a signal by a feedback circuit so as to realize a wider bandwidth and speeding up.
However, even in the feedback type high-speed amplifier circuit, a parasitic capacitance of the added feedback circuit further causes deterioration of a band and jitter increase, bringing difficulty in realizing sufficient speeding up. A factor interfering the speeding up is increase of a parasitic capacitance caused by a feedback circuit (C2 in a formula (5) in Justin Abbott, Calvin Plett, John W. M. Rogers, “A 15 GHz, 1.8V, Variable-Gain, Modified Cherry-Hooper Amplifier”, IEEE 2005 CUSTOM INTEGRATED CIRCUITS CONFERENCE, 22-5-1 to 22-5-4, p.645 to p.648). Especially, a base parasitic capacitance of a transistor of the feedback circuit is the main factor of deterioration. Further, the speeding up is performed by performing subtraction from a main signal by a feedback circuit. However, not only low-speed components but also high-speed components are subtracted in this configuration. Therefore, the high-speed components are further deteriorated, causing difficulty in realizing of a wider bandwidth and speeding up.
According to an aspect of the invention, an amplifier circuit includes an amplifier circuit that emitter-grounds a first transistor that amplifies an input signal; and an emitter-grounded feedback circuit in which a collector of the first transistor is connected to an output line of the amplifier circuit and a base is wiring-connected only to the output line by using a resistor.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
Preferable embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
This amplifier circuit 100 includes a differential amplifier circuit 101 and a feedback circuit 102. The differential amplifier circuit 101 includes a pair of (two pieces of) transistors Tr1 and Tr2, two pieces of loads (resistors) 111 and 112, a current source 113, two pieces of input terminals (inp) 114 and (inn) 115, and two pieces of output terminals 116 and 117.
A base of the first transistor Tr1 is connected with the first input terminal 114. A collector of the first transistor Tr1 is connected with one end of the first resistor 111 and with the second output terminal (signal line outn) 117. A base of the second transistor Tr2 is connected with the second input terminal 115. A collector of the second transistor Tr2 is connected with one end of the second resistor 112 and with the first output terminal (signal line outp) 116.
The other end of the first resistor 111 and the other end of the second resistor 112 are commonly connected with a power source terminal 118 to which power source voltage VDD is applied. Emitters of the first transistor Tr1 and the second transistor Tr2 are commonly connected and are connected to the current source 113 which is provided between the emitters and a power source terminal 119 to which power source voltage VSS is applied.
The differential amplifier circuit 101 having the above-mentioned configuration amplifies a difference between signals which are inputted into a pair of input terminals 114 and 115 and outputs signals having mutually different phases (a positive phase and a reversed phase) from a pair of output terminals 116 and 117 respectively.
The feedback circuit 102 includes a pair of (two pieces of) transistors Tr3 and Tr4 for a differential operation, a current source (tail current source) 121, and two pieces of resistors 122 and 123. Collectors of the transistors Tr3 and Tr4 are respectively connected with the positive phase signal line outp and the reversed phase signal line outn. The positive phase signal line outp is coupled to a base of the transistor Tr3, which is connected to the positive phase signal line outp, via the resistor 122. The reversed phase signal line outn is coupled to a base of the transistor Tr4, which is connected to the reversed phase signal line outn, via the resistor 123. These resistors 122 and 123 are respectively connected between the base of the transistor Tr3 and the positive phase signal line and between the base of the transistor Tr4 and the reversed polarity phase signal line in series.
The transistors Tr3 and Tr4 of the feedback circuit 102 have such configurations that a signal inputted into the collector and the base travels through the identical signal line (outp, outn) and the signal is directly fed back to the differential amplifier circuit 101. Therefore, the differential amplifier circuit 101 is enabled to directly widen a bandwidth of an inputted signal and thus perform a high-speed operation, without being affected by a deterioration effect of a non-linear component of the feedback circuit 102, a limiter, and the like.
According to the above-described configuration, it is possible to shield a parasitic capacitance C2 of the bases of the transistors Tr3 and Tr4 of the feedback circuit 102 by the resistors 122 and 123 provided to the feedback circuit 102. Accordingly, it is possible to exclude deterioration imposed on the signal lines outp and outn.
Further, a RC filter composed of the resistors 122 and 123 and the parasitic capacitances C2 of the bases of the transistors Tr3 and Tr4 is obtained and only low-frequency components are fed back to be subtracted from a main signal (signal line). Accordingly, it is possible to suppress lowering of high-speed (high frequency range) components in the subtraction amount in the feedback circuit 102 and further realize a wider bandwidth of the frequency property and speeding up of an operation.
Further, the configuration that allows current adjustment of the current sources 113 and 121 depicted in
On the other hand, the feedback type differential amplifier circuit of the embodiment is capable of suppressing lowering of high frequency range components and improving the frequency property in the high frequency range, being able to flat the frequency properly over a wide frequency and widen a bandwidth of the frequency property to a bandwidth f2. A band is expressed by a frequency range from a peak of the amplification factor to the amplification factor obtained by lowering the amplification factor by a predetermined level (3 dB), for example.
According to the first embodiment described above, the resistor is serially-provided between the base of the feedback circuit which is added to the differential amplifier circuit and the signal line, so that the parasitic capacitance of the base of the feedback circuit is shielded by the resistor, being able to largely reduce an effect of the parasitic capacitance and realize a wider bandwidth. Further, the serial resistor and the parasitic capacitance of the base serve as a RC filter, enabling the feedback circuit to feed back and subtract only low frequency components. Accordingly, it becomes possible to avoid deterioration of high-speed (high frequency range) components, subtract only low speed components, and speed up an operation.
Further, the feedback circuit 102 uses bipolar type transistors Tr3 and Tr4 and signals of collectors and bases of the transistors Tr3 and Tr4 have voltage of the same polarity, so that potential reversing between the base and the collector in the bipolar type transistors Tr3 and Tr4 does not occur.
The amplifier circuit 101 includes one piece of transistor Tr1, one piece of resistor 111, one piece of input terminal (in) 114, and one piece of output terminal 117.
A base of the first transistor Tr1 is connected with the input terminal 114. A collector of the first transistor Tr1 is connected with one end of the resistor 111 and with the output terminal (signal line out) 117. The other end of the resistor 111 is connected with the power source terminal 118 to which power source voltage VDD is applied. An emitter of the first transistor Tr1 is ground-connected to the power source terminal 119 to which power source voltage VSS is applied.
The feedback circuit 102 includes one piece of transistor Tr4 and one piece of resistor 123. A collector of the transistor Tr4 is connected to the signal line out. Further, the signal line out is connected to a base of the transistor Tr4 which is connected to the signal line out, via the resistor 123. Namely, the resistor 123 is connected between the base of the transistor Tr4 and the signal line in series. The transistor Tr4 of the feedback circuit 102 has such configuration that a signal inputted into the collector and the base travels through the identical signal line (out) and the signals is directly fed back to the amplifier circuit 101.
According to the above-mentioned configuration, provision of the feedback circuit 102 similarly to the first embodiment brings the advantageous effect same as that of the first embodiment in the amplifier circuit 101 of single amplification as well. Namely, the resistor 123 provided to the feedback circuit 102 is capable of shielding the parasitic capacitance C2 of the base of the transistor Tr4 of the feedback circuit 102. Accordingly, it is possible to exclude deterioration imposed on the signal line out.
Further, a RC filter composed of the resistor 123 and the parasitic capacitance C2 of the base of the transistor Tr4 is obtained, so that only low frequency components are fed back and subtracted from a main signal (signal line). Accordingly, it is possible to avoid lowering of high-speed (high frequency range) components in a subtraction amount in the feedback circuit 102 and further realize a wider bandwidth of a frequency properly and speeding up of an operation.
A signal line on to which the collector of the transistor Tr1 of the differential amplifier circuit 101 and the collector of the transistor Tr4 of the feedback circuit 102 are connected is connected with a base of a fifth transistor Tr5 which is included in the emitter-follower circuit 501. A signal line op to which the collector of the transistor Tr2 of the differential amplifier circuit 101 and the collector of the transistor Tr3 of the feedback circuit 102 are connected is connected with a base of a sixth transistor Tr6 which is included in the emitter-follower circuit 501.
Collectors of the transistors Tr5 and Tr6 constituting the emitter-follower circuit 501 are connected to the power source terminal 118 to which power source voltage VDD is applied. Further, emitters are respectively connected to a current source 502, which is provided between the emitter of the transistor Tr5 and the power source terminal 119 to which power source voltage VSS is applied, and to a current source 503, which is provided between the emitter of the transistor Tr6 and the power source terminal 119. Further, the emitter of the fifth transistor Tr5 is connected with the second output terminal (outn) 117 and is connected with the current source 502 which is provided between the emitter of the transistor Tr5 and the power source terminal 119 to which power source voltage VSS is applied. The emitter of the sixth transistor Tr6 is connected with the first output terminal (outp) 116 and is connected with the current source 503 which is provided between the emitter of the transistor Tr6 and the power source terminal 119 to which power source voltage VSS is applied.
The base of the transistor Tr3 of the feedback circuit 102 is coupled with the positive phase signal line (outp) via the resistor 122. The base of the transistor Tr4 of the feedback circuit 102 is coupled with the reversed phase signal line (outn) via the resistor 123.
According to the third embodiment described above, the emitter-follower circuit which is provided on the output stage does not have a voltage gain and enables a wider bandwidth and speeding up without being affected by an effect of a non-linear component of a signal component, a limiter, and the like while maintaining a signal waveform.
Here, the amplifier circuit 100 of the respective embodiments described above is capable of easily adjusting a feedback amount in the feedback circuit 102 because the differential amplifier circuit 101 of a signal system and the feedback circuit 102 of a feedback system are independently provided.
According to the above-described configuration, the resistor 601 which is provided between the emitters of a pair of transistors Tr3 and Tr4 of the feedback circuit 102 enables enhancement of linearity of a feedback signal and suppression of an effect of a non-linear component of a signal component, a limiter, and the like. Further, it is possible to realize a wider bandwidth and speeding up while maintaining a waveform of an inputted emphasis signal or the like.
The adder circuit 1101 includes a pair of input terminal (in2p) 114b and (in2n) 115b. A collector of a transistor Tr1b of the adder circuit 1101 is connected to the signal line on and the resistor 111, and a collector of a transistor Tr2b is connected to the signal line op and the resistor 112.
In such configuration as well, the resistor 601 which is provided between the emitters of the transistors Tr3 and Tr4 of the feedback circuit 102 is capable of suppressing a non-linear component of a feedback signal component, a limiter, and the like. Especially, when such configuration is employed that an emphasis signal is generated by using the adder circuit 1101, it is possible to feed back a signal while maintaining the emphasis signal due to an effect of improvement of the linearity by the resistor 601 provided between the emitters. Therefore, it is possible to realize a wider bandwidth and speeding up while maintaining a waveform of this emphasis signal and the like.
In a circuit depicted in
As depicted in
Further, the provision of the emitter-follower circuit 501 enables widening of a band with respect to the laser element 1201 and supply of a driving signal which is speeded up without receiving an effect of a non-linear component of a signal component, a limiter, and the like while maintaining a waveform of an outputted signal.
According to the respective embodiments described above, a resistor is connected to a base of a transistor of the feedback circuit in series, being able to obtain an advantageous effect to suppress the parasitic capacitance C2 by a shield of this resistor. Further, this resistor functions as a RC filter with a parasitic capacitance of a base of a transistor, thereby simultaneously providing an advantageous effect of reduction of high frequency range components in a subtraction amount by feedback.
Further, a passive device which is a resistor is used for a feedback system, so that a signal is fed back via no other active circuits. Therefore, high-speed amplification while maintaining a waveform of a signal is enabled in a manner to hardly receive an effect of a limiter circuit and a non-linear circuit.
Though the example in which the bipolar type transistors are used is described above in the respective embodiments, in addition to or in replacement of this configuration, the configuration in which other semiconductor elements such as FETs are used may be employed. In the case using FETs as well, the configuration in which a resistor is connected between a gate and a drain enables cancellation of a parasitic capacitance of the gate, realizing a wider bandwidth and speeding up.
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Patent | Priority | Assignee | Title |
11482973, | Feb 10 2020 | SK Hynix Inc. | Receiving circuit, and semiconductor apparatus and semiconductor system using the same |
Patent | Priority | Assignee | Title |
7091773, | Jul 28 2004 | XILINX, Inc. | Limiting circuit with level limited feedback |
8089316, | Oct 08 2009 | SAMSUNG ELECTRO-MECHANICS CO , LTD | Wideband active circuit with feedback structure |
20030214356, | |||
20110181271, | |||
20120062143, | |||
JP2011155368, | |||
JP2011223586, | |||
JP201280061, | |||
JP619312, |
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